This invention relates to a load-supporting structure such as a table, seat, bench, shelf and the like, having an adjustable load-supporting surface. More particularly, it relates to a load-supporting structure having a latching mechanism which permits the load-supporting surface to be readily adjusted when no weight is on this surface, but which prevents disengagement of the latching mechanism and precludes movement of the load-supporting surface when weight or pressure is applied thereto.
Adjustable load-supporting structures are commonly used in home and industry. Examples of such structures include work benches and tables, seats and chairs, shelving, overbed tables, and the like. Thus, such structures may be used in association with a working surface of a fixed height to permit a person to adjust the height of a seating surface to an individual requirement. Alternatively, it may be desirable to adjust the height of a working surface relative to the height of the person working on such a surface.
To be satisfactory, an adjustable load-supporting structure must be capable of being readily adjusted to a number of predetermined positions. In addition to ease of adjustment, it is also necessary that such structures be provided with mechanisms which prevent movement of the load-supporting surface when a load is placed thereon, and which prevent accidental release of the adjusting mechanism while a load is on the load-supporting surface. Heretofore, this combination of requirements has been difficult to achieve in commercially available adjustable load-supporting structures. Thus, structures which are securely held in position when the load-supporting surface is occupied tend to be difficult to adjust. Structures which have mechanisms to permit the load-supporting surface to be readily adjusted frequently cannot be prevented from being released when weight is on this surface.